Developing and deploying new sensors for in-situ monitoring of clouds

Clouds interact with solar and terrestrial radiation, which contributes to competing heating and cooling effects on the climate system. Clouds generate precipitation, and so impact on the spatial distribution of water on the Earths surface. Clouds also facilitate complex chemical reactions and remove pollutants from the air. Datasets are required to capture the microphysical properties of clouds, namely the number, size and shape of the constituent particles, in order to correctly assess the impact and potential sensitivities of clouds on the Earth System. New networks are being established to monitor clouds. Whilst there are numerous options for instrumentation for measuring aerosol particles and much larger drizzle/precipitation particles, there is lack of suitable instrumentation for surface-based monitoring of liquid droplets which constitute the majority of clouds near the Earth's surface.

PhD Project Methodology

Cloud particles have been measured using a variety of techniques over the past 50 years, including bulk sampling of populations, and detailed single particle measurements. However, these existing instruments have generally been developed for operation from research aircraft travelling at high speed, with aspiration provided by the motion of the aircraft through the air. This makes many of these systems unsuitable for ground-based monitoring. Some ground-based fog monitoring systems have been developed, but there are issues over data quality and sampling artefacts resulting from aspiration.

This project will develop and test new prototype sensors for surface-based cloud monitoring. Rapid prototyping will be conducted using 3-d printing and off-the-shelf optoelectronic components (diode lasers, laser drivers, optics, mounts) and Arduino-type microprocessors. The new sensors will be tested in the laboratory using certified glass calibration micro-spheres, Drop-on-Demand particle generators, and polydisperse particle suspensions using a nebuliser system. The sensors will be operated from the Holme Moss atmospheric observatory to monitor ambient clouds. Numerical simulations using Mie scattering code will be conducted to understand the response of the new sensors.


PhD Project Description & Objectives
This project will focus on the design, construction, and evaluation of new prototype sensors suitable for long term monitoring of the droplet size distribution in ambient clouds (diameter ~2-50).

Objective 1: Financial and operational assessment of potential sensors. Assess various sensor configurations including bulk vs single particle, illumination wavelength(s), geometry, measurement principle e.g. scattering/diffraction, aspiration.

Objective 2: Design and Construction of prototype sensor(s). Design and construct the optical, electrical, mechanical and data system for the prototype sensor. This includes construction of a numerical model to describe the theoretical operation of the sensor.

Objective 3: Characterisation of prototype sensor(s). Use a variety of systems such as calibration microspheres, nano-litre Drop-on-Demand systems, intercomparison Mie scattering OPCs such as the DMT Cloud Droplet Probe available from the University of Manchester.

Objective 4: Deployment of prototype sensor(s). Install and operate the prototype sensor(s) from the Holme Moss Hilltop Atmospheric Observatory, operated by the University of Manchester, to obtain data from ambient clouds in real-world conditions. Additional deployments may also be possible.

Objective 5: Evaluation of sensor performance. Data analysis to establish if the real-world performance of the sensor fulfils design criteria. Are the measurement principles sound? Do data appear consistent with broader knowledge of cloud microphysical properties? Are ambient data consistent with calibrations and other datasets? Identify future improvements to the design.

Aerosol science has a significant impact on a broad range of disciplines, extending from inhaled drug delivery, to combustion science and its health impacts, aerosol assisted routes to materials, climate change, and the delivery of agricultural and consumer products. Estimates of the global aerosol market size suggest it will reach $84 billion/year by 2024 with products in the personal care, household, automotive, food, paints and medical sectors. Air pollution leads to an estimated 30-40,000 premature deaths each year in the UK, and aerosols transmit human and animal infections. More than 12 million people in the UK live with lung disease such as asthma, and the NHS spends ~£5 billion/year on respiratory therapies. Many of the technological, societal and health challenges central to these areas rely on core skills and knowledge of aerosol science. Despite this, an Industrial Workshop and online survey (held in preparation for this bid) highlighted the current doctoral skills gap in aerosol science in the UK. Participating industries reported that only 15% of their employees working with aerosol science at doctoral-level having received any formal training. A CDT in aerosol science, CAS, will fill this skills gap, impacting on all areas of science where core training in aerosol science is crucial.

Impact on the UK aerosol community: Aerosol scientists work across governmental policy, industrial research and innovation, and in academia. Despite the considerable overlap in training needs for researchers working in these diverse sectors, current doctoral training in aerosol science is fragmentary and ad hoc (e.g. the annual Fundamentals of Aerosol Science course delivered by the Aerosol Society). In addition, training occurs within the context of individual disciplines, reinforcing artificial subject boundaries. CAS will bring coherence to training in the core physical and engineering science of aerosols, catalysing new synergies in research, and providing a focal point for training a multidisciplinary community of researchers. Working with the Aerosol Society, we will establish a legacy by providing training resources for future researchers through an online training portal.

Impact on industry and public-sector partners: 45 organisations have indicated they will act as CAS partners with interests in respiratory therapies, public health, materials manufacturing, consumer and agricultural products, instrumentation, emissions and environment. Establishing CAS will deliver researchers with the necessary skills to ensure the UK establishes and sustains a scientific and technical lead in their sectors. Further, it will provide an ideal mechanism for delivering Continuing Professional Development for the existing workforce practitioners. The activity of CAS is aligned to the Industrial Strategy Challenge Fund (e.g. through developing new healthcare technologies and new materials) and the EPSRC Prosperity Outcomes of a productive, healthy (e.g. novel treatments for respiratory disease) and resilient (e.g. adaptations to climate change, air quality) nation, with both the skilled researchers and their science naturally translating to long-lasting impact. Additionally, rigorous training in responsible innovation and ethical standards will lead to aerosol researchers able to contribute to developing: regulatory standards for medicines; policy on air quality and climate geoengineering; and regulations on manufactured nano-materials.

Public engagement: CAS will provide a focal point for engaging the public on topics in aerosol science that affect our daily lives (consumer products, materials) through to our health (inhalation therapeutics, disease transmission and impacts of pollution) and the future of our planet (geoengineering). Supported by a rigorous doctoral level training in aerosol science, this next generation of researchers will be ideally positioned to lead debates on all of these societal and technological challenges.